Shearing blind ram assembly with a fish pocket

ABSTRACT

A shearing blind ram assembly is disclosed and includes a recessed area or pocket in the ram bodies into which the sheared ends of the pipe or fish can be received to ensure complete closure of the shearing blind ram assembly and proper sealing of the blowout preventer bore.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a shearing blind ram assembly with a fish pocket for use in a ram-type blowout preventer used in oil and gas drilling operations. Ram-type blowout preventers are part of a pressure control system used in oil and gas drilling operations to control unexpected well bore pressure spikes or kicks as they are commonly referred to in the industry.

The blowout preventer has a body with a vertical bore and a pair of laterally disposed opposing bonnet assemblies. Each bonnet assembly includes a piston which is laterally moveable within the bonnet assembly by pressurized hydraulic fluid. Replaceable sealing elements called packers are mounted on the ends of the pistons which extend into the blowout preventer bore. When these pistons are moved to a closed position, commonly referred to as “closing the blowout preventer” or “closing the rams”, the vertical bore of the blowout preventer is sealed and the kick is contained. These packers are available in a variety of configurations designed to seal the blowout preventer bore when the opposing pistons are moved to their closed position. One type of packer has ends designed to seal around pipe of a specific size in the blowout preventer bore when the blowout preventer is closed. Other rams are designed to shear through a drill pipe section extending through the vertical bore and seal off the bore. It is this type, commonly referred to as shearing blind rams, to which the present invention is directed.

These shearing blind rams must be able to shear through a piece of drill pipe in the blowout preventer bore during an emergency and then seal against each other to contain the well bore pressure during a kick. The opposing shearing blind rams must maintain a pressure tight seal during the kick until the well bore pressure, which can reach several thousand pounds per square inch, can be controlled. Control of this well bore pressure is acquired by use of the kill and choke lines which are part of the blowout preventer stack into which the blowout preventer is installed. The shearing blind ram has various rubber seal elements attached to it to ensure a complete seal of the blowout preventer bore when closed.

In order for the shearing blind ram assembly to operate properly, the opposing shearing blind rams must be able to completely close so the sealing elements attached to the opposing rams can come into contact and seal the bore effectively. Sometimes the opposing shearing blind rams are unable to completely close because the ends of the pipe sheared interfere with the movement of the opposing rams preventing them from completely closing. This inference often comes about because of the crushing and distortion of the ends of the sheared pipe. The ends of the sheared pipe are usually substantially flattened during the shearing process and are referred to as “fish.” The flattened fish can interfere with the aforementioned closing and sealing operations due to their distorted and somewhat unpredictable shape not fitting into the usually rounded shape of the shearing blind ram. The shearing blind ram assembly of the current invention offers a substantial improvement by offering a unique specifically shaped area or pocket into which the fish end of the sheared pipe can be received and thereby allow the rams to fully close and perform the above described critical sealing operation.

2. Description of Related Art

Various types of shearing blind rams with various blade seals have been shown and used.

U.S. Pat. No. 3,766,979 to J. T. Petrick shows a well casing cutter uitilizing O rings to seal around the casing being cut.

The ram-type blowout preventer shown in U.S. Pat. No. 3,817,326 to M. J. Meynier III discloses a blade seal with the rubber element bonded to a metal member.

U.S. Pat. No. 4,081,027 to T. X. T. Nguyen. shows a shearing ram for hydrogen sulfide service utilizing a rubber element bonded to the shear ram to seal after shearing.

The wellhead shearing apparatus shown in U.S. Pat. No. 4,341,264 to F. H. Cox et al. discloses a rubber element bonded in a recessed groove in a shearing ram to act as a blade seal.

U.S. Pat. No. 4,347,898 to M. R. Jones shows a shear ram blowout preventer utilizing a rectangular seal in the lower face of the upper ram as a blade seal.

A shearing ram utilizing a pair of hardened points to aid in initiating the shearing action is shown in U.S. Pat. No. 4,537,250 to J. N. Troxell, Jr. A plain rectangular seal acts as a blade seal.

The shear ram apparatus shown in U.S. Pat. No. 4,540,046 to S. W. Granger et al. discloses a blade seal with the rubber element bonded to a metal member.

U.S. Pat. No. 5,005,802 to D. J. McWhorter et al. shows a variable bore packer for a ram type blowout preventer.

U.S. Pat. No. 5,360,061 to L. M. Womble shows a blowout preventer with tubing shear rams designed to control the shape of the sheared pipe end.

The shear ram apparatus shown in U.S. Pat. No. 5,515,916 to T. D. Haley discloses a blade seal with the rubber element bonded to a metal member and a metal insert in the rubber element to aid in sealing.

U.S. Pat. No. 5,713,581 to D. W. Carlson et al. shows a blade seal of nitrile rubber with uniformly dispersed synthetic, non-cellulosic fibers to aid in preventing seal rollover.

U.S. Pat. No. 6,158,505 to R. Araujo shows a blade seal design utilizing a pair of tapered blade seal elements to effectuate sealing.

U.S. Pat. No. 6,719,042 to C. D. Johnson et al. shows a blade seal design utilizing a pair of square cross section blade seal elements secured to the lower blade to effectuate sealing.

SUMMARY OF THE INVENTION

The shearing blind ram assembly of the present invention is designed for use in a standard ram-type blowout preventer used in oil and gas drilling operations. The blowout preventer has a body with an axial bore, a pair of opposing bonnet assemblies and a pair of opposing rams laterally moveable within guideways in the bonnet assemblies by a pressurized fluid source to control flow of well fluids through the blowout preventer body axial bore. The shearing blind ram assembly includes an upper ram assembly and a lower ram assembly having top seals and side seals for sealing in a guideway of the blowout preventer bonnet assembly. A blade seal is positioned on the lower face of the upper ram assembly that seals on a mating seal surface of the lower ram assembly when the shearing blind ram assembly is closed.

The upper ram assembly includes an upper ram body with a front face shearing a pipe disposed in the blowout preventer bore and a lower face designed to receive the lower sheared end of the pipe. Similarly, the lower ram assembly includes a lower ram body having a front face complementary to the front face of the upper ram body and a upper face designed to receive the upper sheared end of the pipe. The lower face of the upper ram body and the upper face of said lower ram body for receiving the sheared pipe ends include a pair of laterally disposed pockets connected by a shallow curved rear surface to receive sheared pipe ends.

A principal object of the present invention is to provide a shearing blind ram assembly designed for use in standard ram-type blowout preventers used in oil and gas drilling operations that provides a recessed area or pocket into which the sheared ends of the pipe or fish can be received to ensure complete closure of the shearing blind ram assembly and proper sealing of the blowout preventer bore.

These with other objects and advantages of the present invention are pointed out with specificness in the claims annexed hereto and form a part of this disclosure. A full and complete understanding of the invention may be had by reference to the accompanying drawings and description of the preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and advantages of the present invention are set forth below and further made clear by reference to the drawings, wherein:

FIG. 1 is a perspective view with a cutaway section of a typical ram-type blowout preventer used in oil and gas drilling operations into which the shearing blind ram assembly of the present invention has been installed.

FIG. 2 is an exploded view of the shearing blind ram assembly.

FIG. 3 is a partially exploded view of the upper ram of the shearing blind ram assembly shown in an inverted position.

FIG. 4 is a partially exploded view of the lower ram of the shearing blind ram assembly shown in its normally installed orientation.

FIG. 5 is a perspective view from above of the shearing blind ram assembly of the present invention showing the upper sheared pipe moved into the fish pocket.

FIG. 6 is a perspective view from below of the shearing blind ram assembly of the present invention showing the lower sheared pipe moved into the fish pocket.

DESCRIPTION OF THE PREFERRED EMBODIMENT

With reference to the drawings, and particularly to FIG. 1, an isometric view of a ram type blowout preventer 10 used in oil and gas drilling operations is shown. The ram type blowout preventer 10 includes a body or housing 12 with a vertical bore 14 and laterally disposed ram guideways 16. Bonnet assemblies 18 are mounted to the body 12 with bolts 20 and aligned with laterally disposed guideways 16. Each bonnet assembly 18 includes an actuation means 22, including a piston 24 and connecting rod 26. While only one guideway 16 and actuation means 22 is shown, it is understood by those of ordinary skill in the art that there is a pair of opposed guideways 16 and actuation means 22. Connecting rods 26 are connected to upper ram assembly 28 and lower ram assembly 30 to form shearing blind ram assembly 32. Actuation means 22 allows shearing blind ram assembly 32 to be reciprocated within guideways 16.

Shearing blind ram assembly 32 is shown in an exploded view in FIG. 2 to aid in understanding the relationship between the parts. Shearing blind ram assembly 32 includes upper ram assembly 28 and lower ram assembly 30. Upper ram assembly 28 includes upper ram body 34 to which top seal 36 and side seals 38 that seal against guideways 16 are secured. Blade seal 40 is positioned on the lower face of upper ram body 34. Blade seal 40 is of the type shown and claimed in U.S. patent application Ser. No. 10/919,945 filed Aug. 17, 2004 and is incorporated herein by reference. Lower ram assembly 30 includes lower ram body 42 to which top seal 44 and side seals 46 that seal against guideways 16 are secured. Lower ram body 42 includes seal surface 48 that engages blade seal 40 when shearing blind ram assembly 32 is closed.

Referring to FIG. 3, upper ram assembly 28 is shown inverted from its position of FIG. 2 to illustrate the details of its construction. A trapezoidal or “dove tail” shaped groove 50 is machined in lower face 52 of upper ram body 34 and retains blade seal 40 therein. Front face 54 is formed in a shallow “V” configuration at the front edge of upper ram body 34 for pipe shearing and is surface hardened as known to those of ordinary skill in the art to aid is said shearing operation. Lower face 52 of upper ram body 34 has a pair of laterally disposed pockets 56 connected by a shallow curved rear surface 58 disposed at its rear portion. Each of laterally disposed pockets 56 includes curved surface 60 forming a right angle connecting the end of shallow curved rear surface 58 to lateral sides 62 that extend toward front face 54 of upper ram body 34. Laterally disposed pockets 56 and shallow curved rear surface 58 together form fish pocket 64 that provides a space for the sheared end or fish of the pipe to move into after shearing.

As best seen in FIG. 4, lower ram assembly 30 is shown in a partially exploded view in its normally installed orientation to illustrate the details of its construction. Front face 66 is formed in a shallow “V” configuration at the front edge of lower ram body 42 and coacts with front face 54 of upper ram body 34 for pipe shearing in a manner to be described hereinafter. Lower face 68 of lower ram body 42 includes seal surface 48 to seal against blade seal 40 as previously described. Lower face 68 further includes a pair of laterally disposed pockets 70 connected by a shallow curved rear surface 72 disposed at its rear portion, similar to that of upper ram body 34. Each of laterally disposed pockets 70 includes curved surface 74 forming a right angle connecting the end of shallow curved rear surface 72 to lateral sides 76 that extend toward front face 66 of lower ram body 42. Laterally disposed pockets 70 and shallow curved rear surface 72 together form fish pocket 78 that provides a space for the sheared end or fish of the pipe to move into after shearing.

Two views of a typical pipe shearing operation are shown in FIGS. 5 and 6. With shearing blind ram assembly 32 installed in blowout preventer 10, the rams are closed. This causes pipe 80, seen in FIG. 1, to be sheared into upper and lower pipe sheared ends 82 and 84, shown in FIGS. 5 and 6, by front face 66 of lower ram body 42 and front face 54 of upper ram body 34. Fish pockets 64 and 78 provide areas to receive the flattened ends of upper and lower pipe sheared ends 82 and 84 to ensure blind shearing ram assembly 32 moves to its fully closed position and fully seal vertical bore 14 of ram type blowout preventer 10.

The construction of my shearing blind ram assembly with a fish pocket will be readily understood from the foregoing description and it will be seen that I have provided a recessed area or pocket into which the sheared ends of the pipe or fish can be received to ensure complete closure of the shearing blind ram assembly and proper sealing of the blowout preventer bore. Furthermore, while the invention has been shown and described with respect to certain preferred embodiments, it is obvious that equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of the specification. The present invention includes all such equivalent alterations and modifications, and is limited only by the scope of the appended claims 

1. A shearing blind ram assembly for a ram-type blowout preventer used in oil and gas drilling operations, comprising: an upper ram assembly and a lower ram assembly; said upper ram assembly and said lower ram assembly including top seals and side seals for sealing in a guideway of a ram-type blowout preventer; a blade seal positioned on the lower face of said upper ram assembly; said lower ram assembly including a seal surface for engagement with said blade seal when said shearing blind ram assembly is closed; said upper ram assembly includes an upper ram body, said upper ram body having a front face for shearing a pipe disposed in said shearing blind ram assembly and a lower face for receiving the lower sheared end of said pipe; and, said lower ram assembly includes a lower ram body, said lower ram body having a front face complementary to said front face of said upper ram body for shearing a pipe disposed in said shearing blind ram assembly and an upper face for receiving the upper sheared end of said pipe.
 2. A shearing blind ram assembly for a ram-type blowout preventer used in oil and gas drilling operations according to claim 1, wherein: said lower face of said upper ram body for receiving the sheared end of said pipe includes a pair of laterally disposed pockets connected by a shallow curved rear surface to accept the lower sheared end of said pipe; and, said upper face of said lower ram body for receiving the sheared end of said pipe includes a pair of laterally disposed pockets connected by a shallow curved rear surface to accept the upper sheared end of said pipe.
 3. A shearing blind ram assembly for a ram-type blowout preventer used in oil and gas drilling operations according to claim 2, wherein: each of said laterally disposed pockets in said lower face of said upper ram body includes a curved surface forming a right angle connecting the end of said shallow curved rear surface to a lateral side, said lateral side extending toward said front face of said upper ram body.
 4. A shearing blind ram assembly for a ram-type blowout preventer used in oil and gas drilling operations according to claim 3, wherein: each of said laterally disposed pockets in said upper face of said lower ram body includes a curved surface forming a right angle connecting the end of said shallow curved rear surface to a lateral side, said lateral side extending toward said front face of said lower ram body.
 5. A shearing blind ram assembly for a ram-type blowout preventer used in oil and gas drilling operations according to claim 4, wherein: said front face of said upper and lower ram bodies are surface hardened.
 6. A shearing blind ram assembly for a ram-type blowout preventer used in oil and gas drilling operations according to claim 5, wherein: said upper and lower sheared ends of said pipe are substantially flattened during shearing.
 7. A ram-type blowout preventer for oil and gas drilling operations including a shearing blind ram assembly, comprising: a body with a vertical bore; a pair of opposing bonnet assemblies laterally disposed in said body; a shearing blind ram assembly including opposing upper ram assembly and lower ram assembly, said upper and lower ram assemblies laterally moveable within guideways of said bonnet assemblies; said upper ram assembly and said lower ram assembly including top seals and side seals for sealing in said guideways of said bonnet assemblies; a blade seal positioned on the lower face of said upper ram assembly; said lower ram assembly including a seal surface for engagement with said blade seal when said shearing blind ram assembly is closed; said upper ram assembly includes an upper ram body, said upper ram body having a front face for shearing a pipe disposed in said shearing blind ram assembly and a lower face for receiving the lower sheared end of said pipe; and, said lower ram assembly includes a lower ram body, said lower ram body having a front face complementary to said front face of said upper ram body for shearing a pipe disposed in said shearing blind ram assembly and an upper face for receiving the upper sheared end of said pipe.
 8. A ram-type blowout preventer for oil and gas drilling operations including a shearing blind ram assembly according to claim 7, wherein: said lower face of said upper ram body for receiving the sheared end of said pipe includes a pair of laterally disposed pockets connected by a shallow curved rear surface to accept the lower sheared end of said pipe; and, said upper face of said lower ram body for receiving the sheared end of said pipe includes a pair of laterally disposed pockets connected by a shallow curved rear surface to accept the upper sheared end of said pipe.
 9. A ram-type blowout preventer for oil and gas drilling operations including a shearing blind ram assembly according to claim 8, wherein: each of said laterally disposed pockets in said lower face of said upper ram body includes a curved surface forming a right angle connecting the end of said shallow curved rear surface to a lateral side, said lateral side extending toward said front face of said upper ram body.
 10. A ram-type blowout preventer for oil and gas drilling operations including a shearing blind ram assembly according to claim 9, wherein: each of said laterally disposed pockets in said upper face of said lower ram body includes a curved surface forming a right angle connecting the end of said shallow curved rear surface to a lateral side, said lateral side extending toward said front face of said lower ram body.
 11. A ram-type blowout preventer for oil and gas drilling operations including a shearing blind ram assembly according to claim 10, wherein: said front face of said upper and lower ram bodies are surface hardened.
 12. A ram-type blowout preventer for oil and gas drilling operations including a shearing blind ram assembly according to claim 11, wherein: said upper and lower sheared ends of said pipe are substantially flattened during shearing. 